HELP PLEASE WHAT IS WRONG WITH MY DOG?

i have a 9 1/2 year old minature pinscher and hes been acting really wierd.to start off hes has this ballon like lump in his ear its really soft and squishy so im guessing its a broken blood vessel ive already made an appointment.right now hes been real shakey and trembeling on and off,and when he gets up to move he does it really fast whith his bottom down.hes been doing it alot he moves fast like if his bottoms hurts or something and he wont stand up i tryed to get him to and he just ran whith his bottom sorta hanging down and layed on the floor.any idea whats wrong?