I'm 25 years old male and my bmi is 20. Past three months, I had foamy urine, but only in the morning with an urgency to urinate. Specially, I wake up in the morning with a heavy urge to urinate. Therefore, my doctor checked for spot urine test right away in the evening. Test result came back negative for proteins, but my urine was slightly cloudy yellow and calcium oxalate crystals was positive. The doctor said me I have nothing to worry about and just drink lots of water to avoid future kidney stones. However, the doctor prescribed me some medications with vitamin c. Just in case, I took a fasting blood sugar test next day in the morning and result was 90 mg/dl. After that, I took given medicines and my urine went back to normal few days later (no foamy urine). A month later, I got sick with a respiratory infection and the doctor prescribed me some medications with zathrin and deriphyllin. After taking medicines, next day I got foamy urine again, but only in the morning like before.