Blown Motor!?

I just bought a 2007 Civic Si with bolts ons and a tune with around 113,000 miles clocked. Yesterday I was driving home on the highway just cruising at 70mph in 6th and power cut out and a cloud of smoke came out the back and the CEL flashed a few times. There was no abnormal sounds or smell after I pulled over. I also checked my oil and it was definitely low and pretty dirty I had topped it off about a week before and was planning on doing a full oil change very soon after. I limped it to the nearest exit and to a gas station and it was running fine at low rpms and idle. I topped off the oil and continued driving slowly keeping the rpms low. Soon after it cutout again and did the same thing but this time when I hopped out and checked the engine bay there was a some engine knock sound(or some other rattle which I could have assumed was knock because of my paranoia) The engine was only cutting power above ~3500-4000rpm, so I limped it home about 60 miles. It still idles like normal and I checked the codes with an OBDII reader and there was only a coolant temp sensor code which was already there from before. I’m no expert in these things so please help me out if anyone has any ideas on what these symptoms mean.