Q: Doesn't seem to shift down, sluggish when driving.

I have a 2013 Corolla, 82k miles (son used it to get to moving jobs in Florida). When driving it, it doesn't seem like it wants to shift down from 2nd gear so it sounds like it's always idled up. The "check engine" light isn't on. I had the air filter changed couple weeks ago. A mechanic put in another bottle of transmission fluid to see if that would help, it didn't. I've never had the transmission fluid/filter changed or had a tune-up. I had the oil changed a few weeks ago as well. I'm afraid to drive it because I may completely destroy something. I don't know if I need a transmission flush, tune-up or someone suggested filling the car up with better gas and adding a gas cleaner. Not sure that's the problem, but I'll try anything. I don't smell anything when I drive it, it doesn't shake, it just doesn't take off or drive as smooth as it did a couple weeks ago.