Im way too empathetic

I've noticed recently that I'm way too empathetic.

Empathy isn't a bad thing, don't get me wrong, but how strongly I feel for other people is getting out of hand. If I see someone feeling even vaguely sad I will feel it with them, even if it's over something silly. I resonate with peoples feelings so much that its interfering with the things that I need to do because I'm too busy feeling sad or irritated over someone else's problems. Even if I don't know who they are, I will empathise with them.

Someone pointed out the other day that I was limping, and I didn't know what they were talking about, then I noticed that I was I'm was copying someone else's movements (they had broken their leg).

I've tried to stop, but it seems like I can't. Help?