Engine trouble help

[Dallen17]

I have a 1983 Chevy k20 with a good wrench 350 crate motor. I have been having some problems with the truck mysterious losing oil. I've had to put about a quart of oil in the truck everyday for about a week. When I get up for school I find the truck with a few drops leaked out and go to check the oil and it's down to below the low mark on the dip stick. I wondered about the air filter too, so I took off the oil filter and found it had a lot of oil on the filter. I've put a lot of money in the truck and this scares me because I think the motor might be about to blow. If anyone can tell me a little more info and about what to do I'd much appreciated much. Please and thank you!