Bara is a very swedish (maybe germanic at all) way to express.
It would be very weird (I think) to say "y solamente relajándome".
Do you have any other suggestion that matches and doesn't make it weird?
Casper is right, "solamente relajándome" is too weird, if you want to express this kind of restriction you should use a more Latin-like turn of phrase, like:
"Y no hago otra cosa que relajarme"
"Y no hago más que relajarme"
"Y lo único que hago es relajarme"