Sleep regression already?

My LO is 13 weeks old today for the past week he has been sleeping terribly at night. First let me say that his first 5 weeks of life he slept really bad woke every 1 and then wouldn't let us put him down, cried alot!. Then something changed and he started sleeping good getting 4-5 hours at first then waking every 2.5-3 hours after that. Now all the sudden in the past week hes waking every hour and then not going back to sleep after putting him down after his feeding. Could this he the dreaded sleep regression I keep hearing/reading about?. . Anyone else going through this as well?..