You sound kinda like maybe you are a vegetarian? A high-grain vegetarian isn't the most healthy way to go. At least try to eat some eggs for the protein and choline.
Since you are a skinny person, I would recommend that all your meals contain a serving of meat (fish, chicken, eggs, beef, lamb, whatever) a serving of all different vegetables as much as you like, make it heaping, and a serving of some kind of potato or other root thing (celery root, rutabaga, carrots, taro, whatever you want.) Maybe include rice and lentils if you are struggling. They're not Prmal but on all the grains and beans these are least harmful when it comes to the phytates and lectins. Put some butter on the veggies and potatoes and eat nuts liberally for calories. Sounds like you need them. Eat big portions--as much as you want. Think of it like being a ovo-vegetarian that eats meat instead of grains.
The low carb flu lasted for me about 5 weeks and that is because I was older, fatter and had sub-clinical metabolic syndrome. Eating meat, veggies, potatoes, healthy fats and nuts has not only restored me to health but given me a health I never had before, not when I was young, not when I was a vegetarian. I've never felt this good.
Female, 5'3", 48, Starting weight: 163lbs. Current weight: 135.
Starting bench press: 30lbs. Current bench press: 75lbs.