I personally never experienced any side effects from becoming a vegetarian, but that’s not to say it’s not possible. My first suggestion would be to talk to your doctor to make sure it’s not something else (could be genes even).
As far as protein goes, there’s plenty in eggs and dairy, as well as soy, grains, legumes, nuts and seeds. Lots of options! Also, trying to incorporate vegetables that give you the biggest bang for your buck – green leafy vegetables, broccoli, sweet potatoes, cauliflower, brussels sprouts, beets etc. I would recommend some vegetarian diet books to read, but to be honest, I haven’t read one since I was a teen (my mom made me do a class project on how to maintain a balanced diet before becoming a vegetarian. It was written in like 1996, so probably not helpful). You can find a bunch online.