It's normal, as far as I know, to be able to feel your baby's head at that stage. I'm pretty sure I could with my last one. I don't think it is any indication of early labour. However, you could mention it to your midwife or ob at your next visit and ask if he/she thinks that bub is engaged or not.
As far as the pains go, that is likely because when you mess around with the cervix, it causes a hormonal release which triggers contractions. I hope they ease up for you soon!

There was a thread a while ago about checking your own effacement and dilation in late pregnancy. Alan gave some tips on checking your cervix there. I'll see if I can find it back for those who are curious. Just make sure that you always have CLEAN hands! Don't want to risk an infection.

Anyways, maybe someone with more definite information will pop in and give you a better answer about what you should feel at 35 weeks.