Pressure

This only started since the bypass and is the only reason for posting the question here and it's happening more often.  If not medication related could it be blocked arteries in the neck or skull?

There's an incredible amount of pressure in my head.  It doesn't thump and it's not a typical head ache with pain, it's just pressure.  The last times it happened it lasted part of a night, then a few days later it lasted all night, now it's a night and a day and still going on. During the day the pressure wasn't as bad as the night before but this evening it is even worse then last night.  Because of the pressure I may have got three hours of sleep last night.  As it is I could live with this, it's more of a very strong uncomfortable feeling but if it gets worse I'd have to see someone for it.
Double bypass 4-21-09
medication;
Lisinopril: 2.5mg 1/day
Carvedilol: 3.125mg 2/day
Simvastatin: 40mg 1/day
Heart rehab 2/week, not very active at home.

A thought but don't know how valid... I take Ferrous Sulfate @ 325mg ("Equate" Iron pills @64mg) 2/day.  Could it also be problems related to taking these Iron pills for this long?

[RadioAstronomyObserver]

Update!!

  I woke up with an eye problem, the lower half of the upper lid to my left eye is swollen.  My brother just graduated nersing school says this comes from high blood pressure.  My problem is that it's only my head that feels like it's ready to explode and no other part of my body.