Britney Spears is denying she had a "breakdown" at a big hotel in L.A. last week -- but her foot is in fact jacked up ... all of which is quite unrelated to whatever it is she just posted.

The pop star posted a new video (and caption) Monday which brought up last week's ugly incident at the Chateau Marmont ... where paramedics came out after an apparent ruckus in Britney's room, and where she was photographed walking out looking a bit out of sorts.

We'd been told there might've been some kind of altercation between her and her boyfriend -- and that people suspected she was unraveling that night -- but BS is now saying not true.

She writes, "I honestly wish my life was as wild as it has been portrayed !!! Either way, some shit actually has happened to my foot and I might have to get surgery ... fingers crossed, hopefully not but I feel that I was harassed and gaslit and tricked to go on the street when my car was supposed to be there !!!"

Britney adds, "I was in my pajamas and yes, I had been crying because I hurt my foot !!! No breakdown !!! I’m a grown ass woman who is actually very naive in most situations !!!"

She continues ... "I am simply embarrassed they got me in my damn pajamas !!! I don’t feel loved … I feel mistreated !!! With that said, I’m going to treat myself this week !!!"

BTW, with this lengthy description of her version of events -- Brit also uploaded a new video of her going horseback riding from last week ... and her interacting with one of the guys who worked there, to whom she seemed very thankful for bringing her a cowboy hat.

It's a bizarre pairing -- her having fun and being giddy while riding horses, mixed with her denying there was any real issue at the hotel ... and yet, that's exactly what she did.

As we reported ... people in Britney's life feel like she's coming apart at the seams lately -- especially on the financial front, as we've heard she's spending more than she's making.

Some have suggested she needs serious help. Don't tell her that though, she's pushing back.