Hospital. Cocaine is highly caustic to soft tissue and the symptoms your experiencing all point to the need for medical attention. Swelling, redness, puffiness and pain to the touch are red flags. Some slight irritation and bruising following a missed shot is to be expected, but when the irritation turns to pain and the condition does not seem to be improving on its own, you need treatment.
If you really think it's better, than that's your call. If the painful, irritating symptoms subside, then you are probably be in the clear. Just be careful with the cocaine and if at all possible, pursue an alternative route of administration. Cocaine in itself provokes infection and complications, both through the aforementioned caustic nature of the substance and the compulsive urge to redose leads to many needle pokes in short succession, with each poke carrying its own risk.