Cemacbeagles

Hi everyone, Hoping someone can help or at least guide me in the right direction..... I have a 4year old male who has had a normal scissor bite, but in the last few months, I have discovered his bite is now level. Has this happened to anyone before? Does anyone know of any helpful tips to fix it or find out what the cause is. I have heard of things like genetics, rough play, the jaw might be out etc...... Any info would be much appreciated. Chelsea