I can't cum anymore, advise please

I have not cum for a couple of months now. Whether it is oral or otherwise. It is very frustrating. I don't even get wet when I am fooling around with my bf and we have been seeing each other for over a year now. I have never had a problem, usually I am the one initiating things or it is a shared effort because we both are always horny and ready to go when we see each other. Sometimes I used to just get horny just thinking about him. I am 22 and he is 25. I don't understand it at all. Things are fine mentally and physically it seems. I am thinking of asking my gynecologist about it. It is really starting to affect us.