Can Swelling In The Neck Be Due To Allergic Reaction To Medicine?

i recently had a ct scan, with injection of dye not sure what type and i had to drink chromium sulfate as well, that evening the veins onboth sides of my neck have been swollen, is this an allergic reaction? now mind you i have had issues , hence why i had to have ct scan. mind you i recently had gallbladder removal which showed many lesions on it, but unfortunately my doctor believes they have left some behind, and it is causing a great deal of pressure on my body, as if i was bloated and eating is a chore. could that also create this problem...feeling as if i am standing on my head all of the time...