Suggest Remedy For Bumps In Arm

Hello, I was working in the yard on Sunday and I scratched my arm on a fence . No cuts or abrasions at the time. Monday I noticed that in the area where I hit my arm there is a cluster of bumps. No color and they itch if I scratch them. They look as if they could be popped and release fluid. Since I did not know what it was, I have not popped them. The bumps are raised off the skin. The area is about this size of a nickel. Again, it does not itch or hurt. Prior to the branch I was in an area heavy with poison oak. But the rash has not spread. Any ideas of what I m dealing with? Thank you