My question to OP is, what is the effect on your pain? There are different pain receptors that different opioids have affinities for, methadone being the only opioid I know of that binds to all of them.
Why Would I Use Methadone?
That said, I agree with Suzanne that to my knowledge, euphoric effects are usually experienced when the dose is either too large, or administered to/taken by an opioid-naïve patient.
Could be a warning sign I wouldn't ignore.
Doc