Hello dear and welcome to the medhelp forum. This appears to be superficial thrombophlebitis, which is inflammation of vein due to a blood clot located just below skin’s surface. Usually follows injury to the vein or recent IV catheter use. The overlying skin is red and inflamed and warm, there is tenderness along the vein, pain in the limb and hardening of the vein. Consult your physician for a clinical valuation confirmed with Doppler ultrasound. The IV catheter needs to be removed and tip sent for blood cultures to check for any infection. Try putting a warm compress, elevating the limb and over the counter painkillers. Usually this should improve the pain and swelling. Wishing you all the best.
I think it will eventually get better. I, myself have TERRIBLE TERRIBLE veins. Even drawing blood from a butterfly needle is sometimes impossible. I have had soooo many blood draws/IV lines that I have scar tissue in many of my veins. I have had infiltration of the veins from IV lines, WOW, does it hurt!!! Now you have to deal with pain from that aside from the pain you have had before. I have had pain for a few weeks before it went away. Hope it gets better very soon!