Cat keeps pooping on carpet

I've had my cat for about 3 months now. She was very good at first, but then one day decided to poop on the carpet... right in front of the litter box. It started as every other day she would poop on the carpet. The other times she would poop in the box. Now it's become every night.

I have 2 litter boxes, but she doesnt seem to want to use the second one....

Nothing has changed... I use the same exact litter, the litter box hasnt moved, nothing in the area has changed.

I've tried using vinegar in the area and that worked for a few days and then I guess she got used to the smell and stopped caring.

I've tried blocking the area, using tinfoil, and tape on the floor but she just poops right next to the area instead.

I do clean the litter box twice a day.

I am getting very tired of this and don't know what to do... I've researched so much and people keep telling me to go see a behaviorist but I just dont have that kind of money...

PLEASE HELP!!!

change to a nonclumping cat litter. sometimes they don't like the particles clinging to their fur.

Have one box of the clumping kind-then in the other box try the larger particles one. I had a female kitty who pooped on the floor. it was because she didn't like the bits sticking to her fur. we also trimmed her bum hairs too.

Reading your post, I assume that she still uses the litter box but for peeing only. 

If she had constipation or have diarrhea in the past, she may have associated the negative experience with the litter box. Hence some cats would prefer to poop on carpets or other soft materials which creates a more positive tactile experience. 

I recommend visually checking the stool and see if it looks healthy. If not, look to rectify the issue.

If she did have an issue at one point but is now pooping fine, then she may have already developed the habit. Try to add Dr. Elseys' cat attractant or switch to cat attract litter to re-train her. 

Good luck =)

I once had this problem with an outdoor kitten who was sick and had to be taken care of. Well here is my experience, with a tissue I would clean the surface so it smells like the pee and put the tissue inside the little box a bit under the litters. Then I cleaned the surface (a rug) she used to pee and removed the scent with a mixture of water and one drop (very little) of a detergent. It worked for me after one or two failures, but she got it at last. 

Have you tried having two boxes next to each other?

another thing to check is making sure she can bet into poo position in the box?  Mine will go outside the box if her tail is hitting the wall behind the box. To over come this i place my boxes about 10cm from the wall.