I have a lump under my arm pit , been there now since may , not red and it's not sore . i have touched it and it solid / hard .should i be worried ?

Uncertain what it is: Could be a cyst, an inflammed lymph node, ect- if has been there for four months and it is not resolving - consider medical assessment.

Need to examine: It is not feasible to provide a meaningful opinion without examining you. However, you may wish to watch and wait. You may feel the node every couple of weeks, if the lymph gland doubles in size, becomes painful, ulcerates, or other nodes become enlarged, or you develop fever, you should see a doctor. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex. Get HPV vaccine

Yes: It needs evaluation. Possible hidradenitis or benign tumor or carbuncle