I also am losing hair and have been for the past two months. My hair loss started right at three months after surgery. I have talked to my PCP. He said that the stress of surgery and rapid weight loss is most likely the cause since I lost 20 pounds in the first three weeks. I had test and everything was normal; thyroid, B-12, Iron, etc.
There are other posts out here and they all say the same thing, after three months your hair will start to grow back and it will be a thick as it was before unless there really is a deficency so you might want to have the blood work just to make sure all is good.
I am taking Biotin and using Nioxin shampoo. It seems to have slowed down the hair loss a little and I am at the two month point since the loss has started.
I wish you luck, but I am confident that my hair, and yours too, will start to come back in.