Please can someone explain the nature of chest pain associated with acute kidney injury? ive been having mild chest pain when breathing in and out, nausea, passing urine 1/2 times a day, flank pain in both sides, negative for uti on dipstick?

Some systemic diseases affect both systems, pulmonary and urinary, at the same time. Those diseases are not caused by infection so negative UTI by dipstick urine test is not a surprised. Your chest pain is probably due to lung problem, not the heart. You should go to ER or at least urgent care. You need blood tests, a formal urinalysis and CXR. Problem needs to be diagnosed and treated urgently.