Warning: Long, sort of graphic and may be TMI for some...
My DH bought the mylicon (simethicone) and he didn't remember the price but thought around US$9.00 for the bottle. I did a internet seach and found prices of around US$10.00. I think a bottle contains 100 doses.
It says that it's safe enough to use in every bottle, so that's what I'm doing. My LO will kick her legs for 3+hours before a bowel movement and without the mylicon it is very painful (she screams in pain as it comes out). Without it, she wouldn't "go" every day (maybe every 2-3 days) and she would poop three times in a row. After the third one (usually 5-10 minute span), she returns to her normal, happy, smiling self. Before the mylicon, her poos were very thick - like toothpaste or even thicker. And, it would throw her schedule off as well - no nap, no eating; crying & fussy for sometimes 6+ hours before going. With the mylicon, they are much thinner and easier to pass. She'll go every day (actually every night, somewhere between 3am and 6am). More like what people have said to expect a baby to have. She's sometimes fussy beforehand, but more cranky and less crying/screaming.
Finally, we did have an episode once we started the mylicon where our LO had the painful, thick poos again. I'm not sure what happened - if I forgot the mylicon in her bottles or what. At first, I thought that it had stopped working, but last night she did her business without screaming. She did kick her legs and was a bit fussy for about 3 hours beforehand though. Probably wouldn't have noticed if it had been daytime, but it was 3 - 6am! Eventually would like to reset her "poo clock" to the daytime, but for now I'll just settle for pain-free poos!
My pediatrician said to try gripe water and mylicon before resorting to prune juice. I think I'll give the mylicon a few more days and see if it continues to work. I would give your LO's doc a call and see what they recommend for you.