Being unable to approach somebody to learn about them is antithetical to disarming that circular obsession pattern. My advice would be to treat her the same as somebody you could approach and are not nervous around - be that a friend or family member. It is important to keep a person's humanity in mind above petty characteristics they did not choose - such as gender or if they are attractive to you.
Not seeing them anymore is too bad, but it also probably means that any social relationship probably isn't meant to be right now. So in that case take what I say into the future.
Probably need to go to the doctor anyway bruv. I'm 30 and I am not hit with severe back pain. I am hit with mild to moderate pain that eases off throughout the day in response to overexerting myself or sleeping wrong.