Hello,
Firstly, It can be due to vit B deficiency. Take some vitamin B complex for some days and see if your symptoms improve.
Secondly, it can be due to atopic dermatitis or eczema("Atopic" refers to a group of diseases where there is often an inherited tendency to develop other allergic conditions, such as asthma and hay fever). Cheilitis(Inflammation of the skin on and around the lips)is often seen in atopic dermatitis.
Avoid licking the lips as saliva evaporates quickly resulting in them being drier than before. Drink plenty of water and take multivitamin supplements and do not apply lipstick or other cosmetic products for some days. Use a humidifier to moisturize the air in your home and apply shea butter or Vaseline on your lips.
I recommend you see your dermatologist for proper treatment, as that may combine an anti-inflammatory, antibacterial and anti-yeast meds and that you use just plain petroleum jelly for moisturizing. This is particularly important right before bedtime.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
You need to see a doctor and have labs drawn. It could be due to nutritional deficiency or a habit of licking and biting lips, but there is also a specific condition that causes lip changes. I can't remember what it is. See a doctor.