I had unprotected sex with guy a 7 days before my scheduled period. then had period for 5 days and had unprotected sex consistently with guy b 13-15 days everyday after and ended up pregnant. is there any way guy a is the father?

Unlikely: If a woman has sex and then a few days later has her normal regular period at the expected time, then she is not pregnant. When she starts her regular period, her menstrual cycle starts over again, and sperm she got from sex BEFORE her period does not stay fertile through her period. However, if the "period for 5 days" was pregnancy-related bleeding and NOT a menstrual period, then Guy A is papa.