I can see my skin but not other player's skins...

So, basically what happens is that when I go on any type of server, all I see are people with Steve skins. Very rarely do I see someone with a custom skin. I've seen others here with the same issue but the one difference is that I can see my own skin. This same issue happens when I place custom heads in a private world. Still, I can see my own skin. 

I've tried every solution possible. Restarting my game, logging out, updating Java, and changing my resource pack (I don't even normally use one). I guess I may know what the problem is. Recently my Minecraft opens and it just says "Not responding". I found a solution on YouTube. What you do is do to your task manager and click "End Task" on Minecraft but ever since I started doing that, I haven't been able to see skins. I wonder if that could be the possible reason. But, if that is so, I'll have to stop doing that so then Minecraft won't even open.

I hope what I'm trying to say makes since because I really need help. I have no other ideas on how to resolve this.