This is simply false.
> The Constitution prescribes that all spending bills must originate in the House.
Presumably, you mean tax bills, as saying this of spending bills would both be wrong and irrelevant to the issue at hand.
> The ACA originally imposed fees, but as the Supreme Court challenge (NFIB v Sebelius) declared imposing fees would be unconstitutional, but that could be easily circumvented by imposing the fees as a tax, for which Congress has authority.
No, NFIB v. Sebelius [1] upheld the individual mandate as a valid exercise of Congress' taxing power.
It did not strike down a "fee" in the law and say that that "could be easily circumvented" by imposing a tax to replace the fee, as you suggest.
> In that process though, taxes are at the discretion of the House, and the Senate ignored that
No, as noted, tax bills must originate in the House, they are not at the discretion of the House. And, in any case, that's all irrelevant, since, contrary to your mischaracterization, the Supreme Court didn't strike down the PPACA individual mandate and invite Congress to replace it with a tax, it found that it was valid as a tax.
[1] http://www2.bloomberglaw.com/public/desktop/document/Natl_Fe...