I had similar problems over a 48+ hour period last week.
I did all the usual things; new cartridges, changed injection sites, more exercise, increased my dosages (by about 50% at one stage, which was frightening) but it only made small differences. Wondered if I was coming down with something, but there were no other signs.
I have a CGM & would see it start to fall, breathe a sigh of relief only to see it climbing again wihin the hour. I seemed to be stuck at around 13 to 15.
As luck would have it I collected a new prescription on the third day & changed both my Lantus & Humalog to cartridges from the new boxes. It might have been better to change them one at a time to work out which was at fault, but I was getting desperate! My theory is that the Lantus was dodgy but I'd have to go back to the old box to prove it.
This is a very frustrating disease.