hi, i had a very similar prob and it was all down to the cheap guitar i had bought.
when i checked the tuning as it stated in the book, i did'nt realise that the strings where actually far to tight so i was playing in a higher scale so to speak. this coupled with a high bridge and top end meant i had to really push hard on the frets causing all the symtoms you have stated.
it was only when a freind called round and picked it up to play that i found this out, he retuned it and a did'nt have to press half as hard on the strings.
hope this helps