Cruiser bike weird pedaling problems, feels like back tire moving For awhile pedalling my bike has been getting increasingly difficult. First there was a squeaking. I figured maybe because I had put too much force riding uphill. Then there was a screeching cracking sound with the high squeaking. I saw there was just build up and figured that's why there was noises.

I bought oil and grease coated well, and fixed the problem. But then it go worse now the pedals will either get stuck and I have to reset, or it will be very loose feeling like the chain popped off.

Worst of all, now when I bring my foot down to pedal every down motion will make the bike feel like it shifts from the back tire moving left or right, not sure which way. But it's in a side to side motion. I don't feel it while walking the bike.
There is something seriously wrong with your rear hub. From your description I think the bearings have collapsed, and the freewheel mechanism is failing also. This is possibly safety issue - and obviously the bike is not working right, so you need to have it seen to immediately and don't ride the bike until it is fixed.

You will either need a hub rebuild, or a completely new hub. Having one built into the wheel is expensive (it's labor intensive to build a wheel), so it's often easier and cheaper to buy a whole wheel.

It's absolutely impossible to tell you how much this will cost, as we don't know what make/model of bike you have. Do some research, find a reputable bike repair store and they will not rip you off.