Three blowouts in two days, rear wheel only. Twice when you were not on the bike. Even with a new tire.
Two things come to mind based on personal experience.
1) A very fine piece of wire stuck in the tire somewhere. Even the new tire. Would be invisible to the eye, and can only be found by carefully running your thumb around every inch of the inside of the tire before installing a new inner tube. I would also try to locate the hole in the inner tube, and approximate where to look on the tire.
2) Embarrasing to me, but after successfully changing my own flat tires and those of others for 5+ years, I had a similar experience because the new inner tube I was installing on my bike kept getting stuck between the rim and the tire bead. I was in denial and blaming the new inner tubes I was blowing. I returned to the bike shop demanding a refund. The shop manager showed me how I was not paying attention to keep the inner tube from getting pinched between the rim and tire bead.
Now, I take my time. Put a little air in the inner tube before setting the tire bead to keep it from getting stuck between the rim and tire. Then I pump it up to 60 PSI and look carefully at the tire for any signs of 'puckering' in the tire sidewall before I pump it up to full pressure.
Hope you find my 'confession' helpful!