How to differentiate between depression and medication-induced fatigue?

I am planning on getting a new doctor, because I would like to go to someone who does both prescriptions and therapy, instead of just one or the other. So I might wait until I can finally get in to see someone else before I do anything with the medicine.

sometimes it's really hard to tell. Usually I feel like it's either physical exhaustion or mental exhaustion, but sometimes I have these days when no matter what I try to do, I can barely stay awake. As in, if I'm sitting at my table making phone calls, I might accidentally doze off in between phone calls. As long as I'm actively doing something I'm mostly okay, but the second I stop, on those days, I tend to doze off. I don't know if that helps any. A lot of the time, I generally feel like I'm just too tired to do stuff, or like I wake up with no energy, and everything as a struggle, but sometimes I can tell you I feel perfectly fine, but I still feel like I'm too tired to do anything. In the case of the times when I'm falling asleep, I'm pretty sure that that's my antidepressant, or one of my other medications, and then the time when I feel fine but I still feel like I'm too tired to do anything, I'm pretty sure that's the depression, I just don't know what to make of the other day is when I just don't have any energy and can't get anything done. It's probably kind of a dumb question now that I really think about it.