Rash, eczema or baby acne?

My son is almost 5 mo the old. I’ve noticed for the past couple days he’s had some of these small red bumps on his face. Hr just started baby food this past week, so I’m not sure if maybe it’s a reaction to one of those? He does have eczema in the corners of his elbows and behind his knees, could it be that?

it’s not all over his body, just his face.

Any advice or suggestions?