Unsure and concerned

[Thrufaith 9]

Hi so I have been battling with this on and off again skin rash since the end of February. I went to a dermatologist who said it was folliculitis and gave me some antibiotics and antibiotic ointment, as well as a special soap to wash with. Well it didn't work...at least I think it didn't, because the rash would come and go. Mind you this all started after getting fake gel nails and my eyebrows waxed. So I then decided to go see an allergist/immunologist, because I thought this may be triggered by allergies, and she tested me and said that I do have allergies to certain foods and environmental things, but she believes my skin condition is not folliculitis but more a chemical rash reaction to something. So she prescribes this special lotion i have to use on my skin to help the skin repair and heal itself I have to use it for 2 weeks and I am only on day 2. She also ran a bunch of blood work to check for autoimmune conditions (since I already have one hashimotos) and she also is checking for celiacs and my immunoglobulins. I have never had this checked before, and so they call me and say that my antibodies for my immunoglobulins are a little low and that I need to get a booster vaccine for meningitis, pneumococcal, and staphylococcus. I asked  what does this mean and she said oh its not a big deal at all many adults need booster vaccines, and she wants to retest my immunoglobulins 4 weeks after the booster vaccine to see if my antibodies went up! I am like but why is this important? and what does all this mean the doctor keeps reassuring me that this is not a big deal...but I am having a hard time believing that..I googled and scared myself about immunity deficiency diseases and such!  Then my mind starts racing and I think do I have leukemia or lymphoma??? she said all my other blood work looked great (CBC, CMP, ETC..). I am currently freaking out and not sure what to make of all this? I keep fearing the worst like cancer or some type of immune deficiency disease like SAD OR CVID!! any advice or words of encouragement would be great!