A patient with acute respiratory viral infection (3rd day of disease) complains of pain in lumbar region, nausea, dysuria, oliguria. Urinalysis - hematuria (100-200 RBC in eyeshot spot), specific gravity -1002. The blood creatinin level is 0,18 mi-llimole/l, potassium level - 6,4 millimole/l. Make the diagnosis: