Blood in semen

Hopefully I can get some insight on this issue . I first notice this problem last year on my bday and went doctor but the doctor said he didn't see any signs of infection but still gave me antibiotics. basically 2 week ago I was having sex with my gf when I came and realise my cum was bloody there was also no pain upon ejaculation ever since that incident we decided to not do anything but after a week I couldn't help it I decided to check and see if I was still bleeding which at the time look as if I was healing with the blood looking old and brownish fast forward to today we decided to have sex again and to my surprise it was bloody red again. can anyone help me as to what's happening to me

i would get a second opinion it could be something more serious