Sex problems?

Me and my husband tried to sleep together yesterday. He kissed etc and then he put on a condom and just stopped and said that his mind changes and doesn't feel like it anymore. He said it's an effect of these tablets he takes for his stomach problem. This had happened twice now. I just lay there with my clothes off while his mind changes. I try to be supportive and say it's ok and that he should seek help from a doctor. He says no and to leave it alone. I don't think he realises I have needs to and that he should explain his problem instead of ignoring me. Any help or what to do?