Weirdly angry, vicious, and clingy behavior out of our 14 month old?

I hope this doesn't turn into a novel. So LO has always been very high needs, as they say. Demanding would be a good way to describe her personality in general. Very demanding, and dramatic. Lately though, she has added being pathologically clingy and angry/vicious to the repertoire and it's making her very hard to deal with. I don't know what's up with her.She seems to enjoy inflicting pain on us. She will pinch us and smile, or just look at us and it's obvious she's enthralled by the reaction. She digs her nails in when she pinches. She does it to her stuffed animals too, and throws them, bites them, etc. We are not violent toward her or one another so this is coming only from her. She's not learning it from us or anywhere else.Lately, she screams and sobs hysterically if I put her down for a second, even if it's just to pee or something. This happens all the time, except when we are in a store (I try to minimize trips out but I have to grocery shop, etc.) in which case she screams and freaks out until she can walk and then proceeds to try to destroy everything on the shelves. If we tell her no, it seems to increase her desire to continue. If we pick her up, she screams and cries hysterically.She will NOT sit in the cart at stores. If we put her in the basket part, she will spend the entire time trying to destroy or throw out every item we put in.Finally, anytime we try to redirect her, she freaks out insanely, and if we put her in time out or raise our voices/act more sternly, even slightly, to admonish her she cries like someone has abandoned her in a well or something. Lol, just to give a mental image of the hysteria.She is obviously very bright (for instance, she has a book with shapes in it that we read once in awhile, very casually, and today at the store she started pointing out all of the stars on packages and signs, saying, "Star! Star!" -- She woke up this morning after last night's activities, grabbed a random basket and filled it with toys and ran to her daddy and said, "Trick or treat!"... etc.) BUT she does not seem to be learning from the tactics we are using to teach her how to behave. It seems like redirecting her results in a massive meltdown, admonishing her breaks her heart, and putting her in time out scares the shit out of her like she's been abandoned, but none of it teaches her anything about stopping the misconduct.Any advice?? TIA... via /r/Parenting http://ift.tt/2h3Fp0p