Thinning Hair, Not sure what the problem root cause is, greater amount of hair fall, please advise

I’m 17 and recently I’ve been seeing quite a lot of my hair falling, on the floor and on my pillow etc. I also noticed that the hairs are thinner close to the root and some hairs are really really thin. Some hairs come loose when I run through a handful of my hair and it’s really worrying because hair thinning is apparently a very disturbing problem and I have no way whatsoever to leave the house of have a physical examination by a dermatologist. I have no idea whether it’s a shampoo problem or a vitamin deficiency problem or a blood problem because I’ve never really payed much attention to it until now when it seems very apparent that some hair strands are really thin. Please advise on any ways that may help relieve the symptoms or OTC meds that I can get at a local pharmacy, or if these should not work and I should get further professional help. P.S. average hairs that fall per day that I can count are around 50-60 strands I’m guessing because I only pay more attention to the hairs that I grab when running through my hair. I also often wear headphones.