had a cold/sinus infection/whatever since late december; have been medicating myself with Coricidin and Tylenol cold and flu. the last few days i have noticed erection problems. Because of this stuff (i hope!)?
not usually (i havnt heard of it happening at all to be honest)
most cold/flu preparations are fairly generic. they will contain a sympathomimmetic (psuedoephedrine usually), sometimes an antipyritic/analgesic (usually paracetamol), a first generation antihistamine, sometimes an expectorant (usually guaphenesin) or some similar combo of the above
none of those should affect your erection (i sure dont counsel patients that it might happen...no one would take their meds) so its likely something else
just relax, a lot of things can affect your erection, the most common for people in your position is freaking out over not getting one