Painkillers can help to ease the pain accompanied with heel spur/ plantar fasciitis, but it does not offer any cure. Make sure you don't use it just to ease the pain to be able to keep on sporting. Doing so might increase the injury.
Painkillers that are used most often are those with an inflammation inhibitory effect, so-called non-steroïdal anti-inflammatory pain medications (NSAID's), like those containing Ibuprofen.
Make sure to check any side-effects, like stomach problems.