For only 2 weeks, he has tried a lot of things...
Constipating foods - rice cereal for sure (switch to oat or barley), bananas if not really ripe (very ripe are actually laxative), cooked carrots, yams...
Also, remember that LO will need more liquid with these solids too... if you are BFing, maybe offer after solids to see if LO needs a drink
Or, offer a sippy of water.... just don't expect LO to use it very well yet
I would stick to solids once per day for now.. twice is really hard on the tummy and can lead to major sleep disruptions... As a general guideline, best to intro solids in the AM, with lunch offering added after a few weeks, then a dinner offering a few weeks after that. You want to be sure that milk intake remains the same.
Personally, my DD started solids just at 5 months and didn't get to adding in the 3rd dinner time "meal" until 9 months...
And yes - sounds like he is a little backed up