SUV eating QUARTS of Oil like nothing.?

I'm currently driving a 1998 Chevrolet Blazer, has 146K miles on it. The engine though i'd say has roughly 75-80,000, as it was replaced somewhere around 70-75K. The engine does have a small exterior crack in it, and I do (did) have a very very limited oil leak. I was absolutely able to drive 3,000 miles and not have to change my oil, or add any, in-between. Within the last two months I've smelt a very very faint oil smell after I park the vehicle, but recently(last 1.5 to 2 weeks) it's become very strong and pungent.
I live roughly an hour or so from my girlfriend, when I went to visit her one day about half way there I could smell it coming through my vents. I went to a gas station and bought 2 quarts just to get me home. When I opened the valve?(where you pour the oil into the vehicle...sorry i'm not good with cars). The second time I went to see her, I put 3 quarts of oil into the engine. I get to her house, same deal: white smoke, EXTREMELY hot dipstick and it also had black residue on it. I felt like I wasn't going anywhere so I floored the pedal on my way to her house, and I was at 3,000RPMs and can barely muster getting to 45MPH.
My oil gauge is 0, 40 in the middle and 80 to the right(full). It has been between the 0 to quarter tank line now for a while, if that has any indication. When i accelerate though it jumps to the middle or slightly above it?
I'm currently a Col. Senior, with limited funds so i'm scared it's going to cost me a fortune. I'm scared to bring it to a mechanic because I have limited funds to repair the vehicle, and I can't afford purchasing a new vehicle at the current time. I need this thing to last me 10 to 18 more months. After that i'll be set in my career and can FINALLY get a more reliable vehicle. Thanks in advance for any help!

Update: I've let the Blazer sit for 4-5 days, and the oil pressure gauge is reading between 40-50 idling in my driveway.