Feeling slight cramps and back pain 10 days after my period. had unprotected sex 4 days after my period. have a 28-30 day cycle. is it normal?

Not clear: It's not clear why you would be having cramping 10 days after your period. It's possible that since you had unprotected sex 4 days after your period that you're pregnant, though given that you didn't provide any dates, it's not clear how far along you would be. Can take some Ibuprofen for the back pain and cramping and see if that helps.