Sesamoiditis vs. breaking in boots?

I usually wear a 6.5 or 6w (I have a wide toe box) and was feeling some niggling pain in the dip between the big toe and the ball of the foot when I was wearing a size 6 rental skates, and after a session I got measured for a pair of 5.5 Riedell skates. One side fit fine, but the side with the niggling pain went full out into a numb, tingling, painful, and squished feeling. The guy said it’s normal to have pain until breaking in boots, but I just came back from the podiatrist who warned me to take it easy and wear looser footwear with better arch support (I have flat-ish feet) and said the center alignment of skate blades are bound to always put pressure on the ball of the foot.How much of this could be a matter of “breaking in boots” vs. poor fit? Is it safe to go for a bigger size and simply wear different thickness of socks to accommodate for inflammation? Can you switch out insoles of skates, and does it help? Does anyone here get Sesamoiditis and if so, how do you deal with it?Thank you!