Most of the good bacteria are on the sufaces in the tank, not in the water itself (but don't let those surfaces dry out)
As for your filter, if your tank readings are good and it's not an ammonia/nitrite bloom, then let the filter do it's job, which is not just as a bacterial element, but also a crud cleaner. And crud cleaners work better when they get a bit "sticky" - a squeaky clean filter takes less solids out. Three stage filters are great at this, as you can clean one stage at a time, though I appreciate in a tank that size you're probably running a single sponge.
The advice of feeding less is good - just be patient and let the filter get back up to running condition.
If it was me - I'd stop feeding for two days - and take it from there (that way you are at least not adding to it.
(and periodically test your test kit - they can give cranky readings sometimes ........ those silly test strips are way off accurate, but they can and do eleiminate any doubt)
PS - that "bottled cycle" is unreliable .... depends on how it was stored at the shop - how fresh it is - and if that's your problem in the first place ..... too many variables for too much money. You could take what you're spending on that stuff and buy another uncycled filter to run just to take the cloud out if and when it happens.