My husband is bi-polar and when I read your post I thought hmmmm sounds familiar.
The symptoms of bi-polar can very well be other things too I am certainly not saying he is - there are 3 types of BP. Its often misdiagnosed as clinical depression.
If your husband is up for it why not have him evaluated by a psychiatrist? Please steer clear of GP's and the like for any kind of mental disorder lest you end up with a misdiagnosis or incorrect meds. Happens often........
My husband was misdiagnosed for 10 years then by accident, truly accident we found out he was BP in 2011. It has changed our lives. Properly medicated he is a totally different person and has peace of mind Changed my own mind that just eating healthy, vitamins and exercise would do the trick - though they certainly do help now for maintaining his overall health.