Weakness, Fatigue & pain in some joints.

To give a brief history.. I had Covid in 2023 Jan and long Covid symptoms after that. Tingling in my little toe in my left foot and the doctors treated me with Renerve plus & then B active for 3 months.. As I was feeling very weak post Covid. During that time I woke up with my left arm numb and trigger finger.. went to the doctor who asked me to do hot salt water fomentation and which helped me to a large degree.. And he also gave me exercises.. I was largely ok for 2/3 months but now Now there's a recurrence of trigger finger.. and the muscles feel weak.. For the last couple of days I've been feeling fatigue, weakness in my body and pain in joints (fingers, knee sometimes, also when I stretch my right arm out and turn it.. feel a strain & slight pain in inner elbow area (other side).. No fever... I have been walking for 30 minutes for the last one week.. vitamin D level is 55 and B12 is 360.. please advise as to what to do and how to get better..