Welcome to HealthcareMagic forum.
If you have developed the pain and bulging following the intravenous injection, you may be having thrombophlebitis
or localised infection.
Thrombophlebitis is an inflammatory condition which is harmless. It settles down with warm compresses and topical agents like "thrombophobe". I suggest you to try this and plan a visit to your local physician. Antibiotic therapy might be needed to take care of an infection.
Hope this helps.