Edinburgh-based charity Thistle, which has supported people with ME and post-viral fatigue for 15 years, said Long Covid now accounts for 15 per cent of its referrals.
Ahead of mainland Scotland entering Level 0 on Monday, health and wellbeing manager Ross Grieve said the charity has seen a recent increase in demand, including from young people.
It comes after a new study involving Edinburgh University researchers found over half of those hospitalised with Covid develop at least one complication, including over a quarter of adults under 30.
The latest figures from the Office of National Statistics (ONS) show 81,000 Scots living with Covid symptoms for 12 weeks or more, and 34,000 reporting symptoms for more than a year.
Mr Grieve said: "Even people who experienced mild symptoms of Covid, and those who expected to bounce back quickly due to their age and fitness, are finding themselves stuck with ongoing symptoms of fatigue, weakness, disturbed sleep and pain.”
"Some are left behind in their own personal lockdown just as everyone else is benefitting from being out and about more.”
Calum Kennedy, 22, thought he would never recover from Long Covid, and was forced to put his studies on hold because of symptoms including isolation, anxiety and depression.
He became ill in March 2020, in his final year studying Economics at St Andrews University, and has still not recovered.
Fit, active and young, he didn’t have any of the most common Covid symptoms, and until six weeks after falling ill he did not suspect Covid as the cause.
He suffered fatigue, shortness of breath, insomnia and muscle aches from May onwards.
The physical symptoms limited his independence, which he found “extremely challenging” to cope with.
"I noticed a strong link between my mental state and my perceptions of my physical health,” he said.
"With being unwell for so long, I often felt that I was not making progress in my recovery, or that I would never recover at all.”
He added: “It was made harder by not being able to see my friends through lockdown – and when I did speak to them, I didn’t want to dump how bad I was feeling on them. It was hard to access help, as no-one seemed to know what to do with me.”
Mr Kennedy was forced to delay his plans to begin a Masters in Economics at Cambridge University after graduating, and moved back to live with his parents in Edinburgh. He now hopes he can take up his place this year.
Callum O’Dwyer, 29, an engineer from Aberdeen, also fell ill in March 2020.
He too moved back in with his parents, after struggling to cope with the condition on his own.
He experienced severe Covid symptoms in March 2020, which improved after a few weeks, but then suddenly returned.
A month later, he was still experiencing breathlessness, fatigue, brain fog and tremors.
"I felt as though I was wasting away, I had no energy to cook and my whole body hurt as if I’d been hit by a bus,” he said.
"Finally, after five weeks of living alone, I moved back in with my parents. On the first day I could hardly climb the stairs, but not having to worry about cooking and washing-up was a real help. My GPs were sympathetic, but no one seemed to know what to do or how long my symptoms would last.”
He was contacted by Thistle who offered him support, which he is still receiving.
"Like a lot of people with Long Covid, I felt alone and terrified of being left high and dry without any treatment,” he said.
Elspeth McKenzie, 61, works for Sight Scotland and is a gold medal-winning rower from Leith, Edinburgh.
She contacted Thistle after struggling with Long Covid since May 2020.
A keen cyclist, swimmer and rower, she found the symptoms severely limited her physical ability.
She experienced brain fog, stomach pain, headaches and insomnia, which she found “very frightening”, as there was little awareness of Long Covid at that point.
"It was very frightening - I thought I was going mad,” she said.
"I’d had Covid and it was gone! Why had all these weird things started happening? Was it all in my imagination? I kept looking at social media and the news, trying to see if anyone else was experiencing this.
"No-one was talking about Long Covid back then… it was very isolating.”
Ms McKenzie went to A&E in June as she was concerned about feeling breathless. She was told to contact her GP, and also tried NHS Lothian’s post Covid rehab advice line.
Eventually a friend recommended Thistle, which has helped Ms McKenzie manage her recovery.
"If there are three things I want to do in a day, I schedule rest time in between them,” she said.
"My breathlessness has disappeared, and that made a big difference. I know I can keep building myself up if I carefully pace.”
She has returned to yoga and rowing, and has completed a phased return to work.
Mr O’Dwyer hopes to be able to live independently in the next year, and has been able to do some walking and take a trip to the Highlands.
Mr Kennedy has been able to return to some physical activity, and is now confident he will make a full recovery at some point.
Mr Grieve said: “No one has to struggle with this alone. With early support and advice and by making some short-term adjustments, most people are able to recover well and avoid this health crisis becoming a life crisis.”