Greetings, sorry about the pain.
Your description seems to be pointing towards an injury at the arterial and adjoining areas (layers of skin and muscle) It is quite common to happen if finding blood pathways become difficult while taking blood samples.
Next Steps
you had failed to mention if there was any discolouration in the area. nonetheless get a orthopaedic and physiotherapy evaluation to sort this out.
Health Tips
I strongly feel you need a myofascial release by a physio. reason after an injury while in the process of healing underlying structures develop adhesions so after couple of weeks they become stiff. so loosing then will ease pain and get back your underlying structures elasticity. with good support from a physio near your area, you should be better
if any concerns do let me know.