Combo test is pretty accurate after 2 -3 weeks of exposure.
Though we do recommend a test repeat after 3 months as most antibody form after 3 months but it is false to say no test can detect hiv before 3 months.
It your initial day 3 and 1 month test is negative there are very less chance of 3 month test being positive.
Initial symptoms of hiv are
flu like illness and they are non specific
do contact me for further diagnosis and treatment or if you still have some doubts you want to clear.