Noticed last week that i have started to develop a lisp.doesn't matter who i'm talking to, or time of day.i can correct it if i'm trying.what is this?

Evaluation needed: From your description of physical therapy related involvement, I'm thinking there might be a connection of some sort. The providers already involved can evaluate this new symptom and would have possible ways to intervene or know of speech therapists who could. Don't stress or strain too much, but do what you do to self-correct when you notice it. It may be a sign of some neurological-motor changes