Metronidazole is the recoomeded drug of choice
But you are not being much benefited form it . Am aware of your
stress as you have been having symptoms now and then you must be disappointed from taking any more treatment .
However I can give you some tips which might be useful for you as prevention is better than cure .
1.Drink only water that has been treated in established treatment facilities.
If there is any doubt about the adequacy of the treatment of water, boil the water or filter it through a filter with a pore size of
Do not drink from fresh water streams or lakes without boiling or filtering the water.
Do not use ice or drink beverages made from tap water that may be contaminated.
Do not brush teeth with tap water that may be contaminated.
Do not eat uncooked or unpeeled fruits or vegetables grown in conditions in which contamination with Giardia might occur.
Wash hands before eating food, after changing diapers, using the bathroom, or touching pets.
No anal or oral sex