I think my boyfriend is unhappy and doesn't want to tell me. What should I do?

My boyfriend and I have been seeing each other for about 2½ months. Last night, I spent the night at his house, and he had a lot of trouble falling asleep. I heard him get up and take some pills, and eventually he slept on the couch for a while.

I asked him if everything was ok, and he got back in bed for a little while and held me and reassured me that it was. This morning, he said that he thought he was having an allergic reaction to something that was keeping him up, and he took some Benadryl.

I noticed there was also anti-anxiety medication on the counter. He has never mentioned anxiety problems to me, and I think it is his personality style to try to deal with things like that on his own.

I guess I have some trust issues, so I don’t want to let myself jump to conclusions, but it definitely has me fearing the worst. I am worried that the real reason he couldn’t sleep is because he’s unhappy with me/our relationship, but he doesn’t want to hurt me by bringing it up. Otherwise, if he was feeling anxious about something, I don’t understand why he wouldn’t just tell me.

I definitely believe in honesty and open communication. Should I say something to him? If so, how and what?