Advice?

My boyfriend and I have been together for a few months now and anytime I'm with him I'm the happiest I've been in a long time, but anytime I have to leave or leaves I cry even thought I know I'll see him again in a few days ( we see each other 2 sometimes 3 times a week) but despite that I still cry anytime I'm not with him or I feel like I'm going to have a panic attack, this has never happend to me before and I'm not really sure what to do if their is anything I can do about it.