I was sick for a month and lost 10 pounds a lot of which seemed to be muscle. However, I didn't lost much arm muscle and, after two weeks of going through my routine, I am up to par with where I was with my arms.

However, I lost much chest and leg strength and perhaps my back as well but I cannot tell since back workouts seem to be easy with my un-evenly big biceps.

So, would it be a terrible idea for me to work out my legs, chest and back without working out my arms?

by the way I am very much so towards the ectomorph side, idk if that matters but I figured that I would mention it