Usually the effect goes away for people within a few hours, but sometimes it can last a long time. I had a friend who had a mast cell activation flare for over a month due to poison ivy! But her case is unusual. For her, even water would cause symptoms to intensify slightly because the act of ingesting anything triggered the revved-up mast cells, but the first things she could tolerate were sweet potatoes and seaweed, and then white rice. It really should pass soon for you! But if you have any of the remedies I mentioned above, or Benadryl, that might help.
Not to nitpick, but it's important to distinguish between an anti-inflammatory diet and a low-histamine diet, in this case. You want the latter, or both.
There are many very healthy foods that are high in histamine - kefir, sauerkraut, kimchi, kombucha, yogurt, tempeh, miso, many probiotic supplements, anything containing vinegar, tamari, fruit that can be eaten very ripe (like raspberries and bananas), nutritional yeast, citrus fruits, tomatoes, leftovers, mustard, pickles, and more. You will find that not everything affects you, though. A sip of wine or miso would zonk me out for days, but I can eat citrus and tomatoes with no issues.