Here are some reasons why your tama may be acting this way:
1: Pausing a Tamagotchi will really affect his aging process... you might have paused it for these reasons:
A: You could have paused it for activities you can't bring it to: for example swimming, Karate, Gymnastics, Badminton, Soccer, Football...etc.
B: you might have paused it at night...thats not the best plan, BTW.
C: It is possible it got paused by accident; if you lay down on it, or sat on it or somethin, it could have paused without you knowing...
2: You might have gone on clock set by accident... you might have done this for these reasons:
A: You didn't know how to pause
B: Accidently, you could have pressed the B button ( my B button is very sensitive) then A and C and the same time. That would literally stop time!
3: If none of these ever happened, your tama could have a glitch. Here are the reasons it might have a glitch:
A: You could have tried to Debug, or you opened you tama for a preticular reason, and you might have done something you wer'nt supposed to.
B: This is sorta impossible, but one of your friends you connected with might of had a virus and he passed it on to you
P.S: If there IS a virus in your V2, I strongly advise that you either be extremely careful with it, or that you buy another one. You could also contact Bandai.
4: Your tama may be having battery problems.
5: If you reset your tama often, and then download, he w'ont grow very quickly.
I hope my tips have helped. If you have any other questions about V1, V2 or V3 ( depending on the question for V3), I will always be happy to help.
Marie