tongue thrust

Just looking for some input on a 7 year-old client who has a very strong frontal lisp. I'm not sure what the true definition of "tongue thrust" is, so maybe you could call it that, but his tongue just comes through the teeth so prominently. He has a history of ear infections and seasonal allergies and eventually they removed his tonsils and adenoids (I think around age 3), so maybe he was pulling that tongue forward in an effort to breathe better? It almost seems like his lower jaw position has a forward carriage. I have a video of him and would share it if anyone has the capability of viewing it online. In any case, any thoughts, suggestions, referrals I should be making...I've tried a little traditional /s,z/ therapy and even with that, his tongue is jamming up against those front teeth. Would love some input, or if you need more info, let me know! Thanks! Katie