The condition that you describe is likely to be urticaria
(red hives, itchy, feels like lumps on skin, usually not water filled, but if you press hard might leak fluid).
80% of patients with urticaria do NOT have any allergies which may be the same in your case.
Blood tests are usually not helpful, but a full blood count, ESR, liver function, thyroid
function help exclude a secondary cause.
You will need long-acting antihistamines such as allegra
180mg plus/minus cetirizine
10mg for 1 month to see the effect. If this recurs, you must stay on the antihistamines for 3 months.
A skin biopsy
is only required if there is no resolution of the lumps, or there is bruising or scarring.
Hope that helps.