Welcome to this forum. I hope you find a lot of great information here. What you describe sounds quite frightening. Did your first allergist prescribe you an epinephrine autoinjector (EpiPen, Allerject, Auvi-Q)? If not, be sure to get two from your GP and keep them with you at all times. Knowing your allergens or not, allergic reactions can happen any time, no matter how well you try to avoid them. Epinephrine is the only way to stop an allergic reaction from progressing and anyone with a history of food allergy needs to have it on their person. I cannot stress this enough.
In the meantime, steer clear of anything you may be allergic to (soy, peanut, pea, apple, tree nuts, cilantro, sesame), any uncertain foods, and anything that may contain those items. It is rare to develop multiple food allergies all at once as an adult, but it is better to play it safe until your allergist can clearly define what's going on. Sometimes after a big reaction (or even mild ones for that matter), your body can get out of sorts and start reacting to things it normally wouldn't.
Great to hear you have another allergist appointment set up for March. Hopefully this one will be better able to address your concerns, get to the bottom of your reactions, and provide you with better support. I, too, test negative to my allergens (both via blood and skin tests), but false negatives exist. Reaction history trumps all testing. An allergist trained in food allergies should be able to recognise this.