Relationships

Me and my boyfriend of 6 months have recently had sex, it was the first time for both of us and I couldn't of asked for anyone better to share that with, it's just I've been away from him for 2 weeks as I am spending some time with my family in a different part of the country and things have changed between us, I feel as if he doesn't really care about me, we've had some issues in the past with cheating, and being away from him is making me very insecure about that, I don't know what it is but we have been arguing every single day and he's seemed to have just lost interest in me, this is my first serious relationship and I don't know what to do, advice anyone?x