Talk to Pediatric Urologist on Undescended Testicles And Buried Penis

My baby boy is 21 months old. He is chubby , his weight is 15 kg. When he was born he had normal penis. He was 2.6 kgs at that time. After 4 months he started gaining weight and then his penis got buried and its still the same. I didnot know about the undescended testicle at all. Recently knew about this term and I examine him after knowing this term and i think my baby is suffering from this. His scrotum is very small and i cant feel anything in it. Its just skin you can say. Whats the issue with my boy and will he be ok?? Can anyone guide me about treatment? I will take him to the doctor too.