Cabin crew in the rear galley should have felt/heard something, did they say anything to the flight deck crew? As previously mentioned there is no indication on the flight deck of a tailstrike. Tailskid eicas is telling you that the tailskid is not in the position selected ie it extends/retracts with the gear, it is not an indication of a tailstrike.
Noise and rumbles are subjective during takeoff, are the CC trained to interpret a tail strike? e.g. carts unlock, lavatory panels dislodge, overheads pop open, passengers scream etc.