HELP PLEASE

My husband can't climax during sex....I don't know what to do. He couldn't on Wednesday but was able to on Thursday.  However, since Thursday he hasn't been able to climax and we have had sex on Friday and Saturday. Of course yesterday and today are my best chances of conceiving. He has no problem getting it up and going but then nothing. I'm so depressed and I just don't know what to do. I've tried talking to him and he says it feels good but he just can't climax and he doesn't know why.