Sudden Bald Spots

Hello! I've got a very healthy and active 4 year old male cat that I just noticed is having some bald spots issues. He has been shedding a lot and I've been brushing him, but not in these spots. They are on his back legs, on the inside- both of them. He's never had this happen before. 

He was just dewormed a few weeks ago (since he's a hunter) but other than that nothing out of the ordinary. 

His brother developed some serious food allergies along with flea and mite allergies about 6 months ago- when that happened he would (the brother) would get really itchy and pull out hair on his neck and outside hip area. Could it be hereditary? Anyone deal with anything like this before? 

I don't want to stress him out with a vet trip if it's no big deal.

Thanks in advance for any advice. Here's a picture of his normally very fluffy bottom The bald spots are sort of inside his leg area, but there are no sores, no open wounds, bumps, anything strange. It MAYBE looks a tiny bit pinkish but that just might be his coloring too. HELP!

I m a human doctor, not a vet and any advice that I give you about cats should be checked with your vet.

Having written that, feline alopecia (loss of hair) is not uncommon and may be quite benign, possibly due to such things as

over-grooming.  However you should take your cat to your vet because alopecia can occur with such illnesses as thyroid disease as well as a few other, rarer, diseases.

Making a diagnosis from photos is very unreliable, however your cat's skin appears normal where the fur has come out.  Let us know what your vet says, he/she will very likely arrange a blood test to check the thyroid condition.

With all best wishes,

Geoffrey

@Geoffrey  Thanks for your response. I appreciate your input. I will call my vet tomorrow and see when they can get him in for a look.

Took Michaleto to the vet, and with all allergies, it's sort of a trial basis... even though he had no visible signs of fleas, Dr thinks it's flea allergy, as this is most common, especially in the area he's itching and losing hair. Gave us prednisone, which I'm not too excited about, but hope it will clear things up for him. 

Wish us luck!