I can't get any more wacka bumps!! What's wrong?

You should be able to because on the island Keehaul Key if you follow the cliff to the left until you can't move you should see a little blue thing pop up from the ground. Whack him with your hammer and you get a whacka bump. Or your problem may be this: Because it restores 50hp you can only carry 1 at a time.
Hope this helps

Because you gave him a hemmorage!!!!! (hit him too many times)

6 times do you get these bumps and $50 each one is worth so SELL SELL SELL

Sell 5 ,bring one to zess t and cook it

And you can carry more than one at a time

ANYONE WANT TO KNOW HOW TO DEFEAT THE SHADOW QUEEN? WELL FIRST YOU NEED AT LEAST FIVE WHACKA BUMPS AND FIVE ULTR SHROOMS.YOU HAVE TO HAVE AT LEST 20FP AND 100HP.UPGRADE BOBBERY AND VIVIAN AT LEAST ONCE.IF I WERE YOU THEN I WOULD PROBABLY TAKE SOME PRETTY RARE RECIPES IN THERE ALSO.FIRST START OUT WITH BOBBERY.TRY NOT TO USE YOUR LITTLE YOSHI THAT MUCH.EQUIP 2 POWER RUSH PS. EVERY TIME YOU GET 50HP OR 25FP DECREASED,USE AN ULTRA SHROOM OR A WHACKA BUMP.EVERY TIME THE SHADOW QUEEN USES HER 15 HP TAKER ATTACK, USE VIVIAN TO HIDE UNDERGROUND AND KEEP IT FROM HURTING YOU.ONCE YOUR SP REACHES SO THAT YOU CAN DO SUPERNOVA DO IT!NEVER USE ANY OTHER SPECIAL,ONLY SUPERNOVA.USE BOBBERY TO ATTACK WITH REGULAR BOMB EACH TIME.IF BOBBERY AND VIVIAN GET KILLED, USE ANOTHER PARTNER.THE STRONGEST TO LEAST IN MY OPINION GOES BOBBERY, MRS. MOUSE, VIVIAN, FLURRIE,KOOPS ,GOOMBELA,YOUR MINI YOSHI.IF THIS DOESNT WORK TELL ME AND I CAN GIVE YOU SOMETHING ELSE TO TRY.LOVE PAPER MARIO! C YA!

Sell them on the train 100 coins each which means if you still have your 6 and have the train sell there 600 coins baby ya.