Pregnancy is confusing!

Yesterday was Sunday, and a weird day it was! I was pretty tired. I had been having chest pains since Friday morning. This is something weird I had never felt before. I didn't think much of it because it came and went whenever it wanted. By Sunday afternoon, there were times it was so intense, I wondered if I was having heart or lung problems........it really was starting to freak me out! I decided, "What the heck, better safe than sorry!" I went to the ER. I actually saw the DR quite quickly, which for a Sunday, was pretty amazing. They did an ECG, which turned out to be normal. The Dr thought perhaps the baby was squishing my lungs, causing pain. He was really nice about it, and said to come back if I had any more problems.
This morning I was into some cleaning. I washed the bathroom and kitchen floors, and changed my bed. I would have kept going, but because I was scrubbing the bathroom floor on my hands and knees, I began to have pain. I decided I better quit. (I could barely get off of the floor, LOL!) I lie down to rest my aching groin and back, which got better after a short while. I decided cleaning would wait until tomorrow!
This evening after I had come back from Wal-Mart, I had a horrible pain in my lower abdomen. I could barely walk. My lower back has also felt really achy the past few days, like the baby is pressing on my spine and bowels. I went to lie down because I was sooooo uncomfortable, walking hurt! Dave brought me some tylenol, which helped a little bit for my avdominal pain, but I still feel like this baby is pressing my spine and bowel area. (Does that even make sense???!!!) I just know that I wish the back pain would go away, it's so painful at times, the only thing I can do is lie on my bed! I seriously wonder if this is kinda like pre-labor? Or is it just normal pregnancy? I have a feeling I won't know when I am in TRUE labor! (Gee, pregnancy is confusing!!) Well, off to bed I go!