Sounds like either a localised spasm or possibly a pulled muscle. Try, massage, also hot/cold therapy could work. Get an ice pack, put it on the area, for a minute or so (with a towel or similar between you & the pack), then a hot bath, then ice again. Stretching could help too (don't force these "gentle" is the word here as if it is pulled you don't want any more damage). Any, or all of these could be used.
Don't workout that area again until the pain has cleared up, if it continues for any length of time, go see someone about it (just in case).
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