Losi.

This is completely normal. It happens because the shock of surgery and/or rapid weight loss throws your hair into what's called telogen effluvium, which you can look up on Google.

If you have been evaluated for adequate protein levels, that should be the reason.

Chances are, however, that your supplement regimen is utterly inadequate. This is something you need to revisit.

 My dietitian was very specific about PROTEIN ISOLATES only. No concentrates or collagen; our bodies can't absorb the collagen which means it's worthless to take. (The concentrates may have SOME isolates, but since we can't verify how much is isolate and how much is collagen she says to avoid them, w/the exception of Syntrax Dessert brand protein. That's a brand she trusts.)

I really like the Dessert brand banana pudding and whipped cream flavors. I use the chocolate fudge flavor for my shake-cakes (which is a delicious way to get in some protein. I sometimes add a couple tablespoons of peanut butter powder to it and it tastes like a Reese's peanut butter cup.) I don't care as much for the chocolate coconut candy bar flavor, but my daughter likes it, says it tastes like a Mounds bar.

I tried IDS Multi Pro Vanilla Cinnamon a couple days ago and it was really good.

I don't care for the fruity Nectar brand flavors. I've actually made them and had to pour them down the drain, couldn't even choke them down, but I do like their cappuccino, vanilla torte and chocolate flavors.

Stay away from the shots. They are not helpful to you. Get some samples from vitalady if you can. I have a big box of samples that I'm slowly making my way through. I tend to fall back on my faves quite often though. Once you find a fave drinking your protein shakes won't be so dreadful. 

I couldnt tolerate the tastes of the protein drinks for a few months post op and I had purchased a volume of them from Champion Nutrition. On occasion now I can tolerate the coffee protein drink that has been posted here a few times. BUT my point is I have had little to no hair loss (at first it seemed I had more in my brush but that didnt last) and I have been getting my protein from food. Eggs, cheese. cottage cheese, yogurt, cream. chicken, steak, burger, ribs, bacon, nuts, peanut butter, etc etc and enjoying eating all the while. . .

I dont particularly believe you need a lot of protein drinks necessarily to get in enought protein. I wasn't a big meat eater pre-op so I dont think I had  big protein stores either. I know we are all different and react differentl to things but my point is not to forget to consider eating the protein to get it in.