Tmi but I'm freaking out

6 months ago I had EXTREME pain and blood when I pooped. Like crying and holding it in bc shitting hurt so bad. Dr said to take miralax and basically do a colon cleanse (completely empty bowls it's not fun) bc I had built up shit from not going regularly for 10+ years. I did it and it helped for like 5 months but recently it came back and it hurts worse than before. I'm confused bc what I did was supposed to solve the problem- the built up shit is supposed to be gone right? I started taking miralax again but rn I'm super gassy and I literally can't sit bc my ass hurts so bad. I'm scared to try to use the toilet but my lower stomach is killing me and I'm very bloated.