You may have infiltrated the vein and will need to watch for infection due to extravasation. Extravasation is the "leaking out" of fluid that is intended to go into a vein and instead goes into surrounding tissue. It can cause these symptoms you're experiencing. No emergency action is needed at this time for the infiltration. For now, take warm compresses and apply them to the swollen hand. It will help for comfort. Some argue that cold compresses work better for comfort but I'm "old school" and feel that warm is better. Try what works for you.
In the meantime you must watch for signs of infection at the site and for possible phlebitis. Look for red streaks going up the arm over the next few days or and pus or drainage coming from the site. If this occurs, you will NEED to see a doctor for antibiotic treatment. Although it's unlikely, an infected IV infiltration can turn quite ugly and worse case scenario could be loss of you hand. Doctors must abide by confidentiality, so you don't need to worry about anyone finding out.
You should also expect swelling to go down over the next couple of days. Bruising will be normal. Take antibiotic cream and apply it to the site regularly.