Hi,
I apprecaite your observations about your health. They will be very useful throughout your life. It is good that you got the examination done for ruling out infections. Swallowing your sputum will definitely NOT cause the urine to turn cloudy.
A cloudy urine can be caused by precipitation of crystals and amorphous salts. Phosphates and carbonate salts precipitate in alkaline urine and
can be redissolved by acidifying the urine with acetic acid. Uric acid and urates can be redissolved by heating the urine to 60C. Urate salts also dissolve in acidified urine. This is a normal variation and does NOT require any treatment.
Other causes for cloudy urine are: leucocytes(pus), bacteria, red blood
cells, spermatozoa and prostatic secretions in men and mucus secreted from the urinary tract.
Since infections have been ruled out, i would not wory about this, just increase your fluid intake and the urine color ought to improve,
Do remember to accept the reply if you found it useful
regards
Dr. Gupta