It is good that you will have this change in attitude checked out by a vet, because pain will make anyone grumpy. Like an ulcer, that is a real grump maker. It's hard to know if that is the reason, but it's the first to eliminate.
In addition, I would not allow him to approach with his ears pinned. If he walks up to you with his ears pinned, step toward him a tiny bit and slap your thigh and see if he doesn't put his ears up . If he pins 'em more, slap your thight hard and swish him away from you a step or two, and then him turn and look at you to see what the heck you are asking of him. Then invite him to come in and see if he won't come in with a more interested, curious attitude.
Coming toward you is a privilidge. YOu will interupt him if he's walking toward you like he owns you. It is using a very simple to , if necessary, a harsh reminder that he comes when invited and asks "mother may I?" each step of the way.