Why don't you get a thiomeral allergy patch test? That way you'll know one way or another. The T-free vax might be easier to get with a diagnosis. It's important too, since thiomersal is in more than just multi-dose vax's.
It's in some makeup removers, eye shadows and mascaras, soap-free hand liquid and wipes, eye, ear and nose drops/ointments, antiseptic sprays, skin cream/ointment medications and firstaid products. Also the TB test, tetnus jabs, antitoxins like antivenom (although if I had just been bit by a cobra I guess I'd take my chances
) and immune globulin preparations.