Denise, was your husband given any meds for nausea such as Zofran? There are very small tablets that melt under the tongue which really help to curb the nausea from the side effects of chemo.
When someone has a chemo treatment, there’s usually 4 weeks between cycles. The first week after, there’s generally fatigue and some nausea. The 2nd week can be extreme fatigue, more nausea, lack of appetite and ennui and the blood counts drop to very low. By week three, usually the blood numbers start to rise and the patient feels a little better, just in time for the 2nd round. So your husband is most likely at that low stage yet and should be rebounding, though everyone has a different rate of recovery.
I know he doesn’t feel like eating. But if you could have small amounts of food that he can just grab and graze would be helpful.
My husband had little containers in the fridge with bit sized pieces of PBJ sandwhiches or cheese and crackers, chucks of lean meat such as chicken breast, pork roast, he’d have small squares of omelets, etc. That way I didn’t have to face a large dinner plate of food that made me want to upchuck.

You can ask his oncologist to prescribe Zofran or another anti nausea med. There are Queasy Drops or Ginger candies that can help as well.