crowntail betta fish?

[WarMachine]

well when i bought it, it tail was just flowing around and then when we were in the car it just randomely starting hitting the ground and then its fins looked al spikey? why and how does it do that?

(and when i was at petco this bitch lady said "i should get two bettas and watch them fight to the death and she didnt even pronounce betta fish correctly) so yea, please answer the question.
thats when it was in a little jar. now its in my 2.5 gallon tank with filter and its just barley swimming

[Tsunami]

It's normal, he's fine. When put in new surroundings a Betta will often "flare" his tails and dart around quickly. As soon as he realizes he's the only fish in the tank he should calm down and probably will never do that again unless he's seeing his reflection.