Yes I definately get hiccups in my bottom sometimes, or else on either side, I know what side the baby is on then ( it keeps flipping)
I think when you get them in your bottom its head is posterior and lying near your bowels, I was just saying to DHthe other day- never thought I would be feeling hiccups in my bum lol.
When my baby was going from breech to cephalic earlier in the pregnancy I used the hiccups to tell where baby was, so I would be pretty sure yours is head down!