Problems with my Betta eating - can't open his mouth!

Hello. I just joined as I am looking for a solution to my Betta's problem. I have had him for almost 2 years and feed him Hikari Bio-gold. We have been through some illnesses and I thought he was better but he cannot open his mouth wide enough to accept his pellets. I have owned Betta's for years but have never encountered this problem. Does anyone have any advice on what I can do? I have crushed his pellets temporarily but he is not showing any interest. He made several attempts for the whole ones but can't get them in his mouth.
Please note, although no boardcode and smiley buttons are shown, they are still useable

I've replied in your other post.