Rick Simpson oil should use ethanol as the solvent. Any small amount remaining is unlikely to be in a large amount to have any effect, even if it's 50% ethanol (very unlikely) it'll still get you much more stoned than drunk. It was likely something else that made you sick.
If it's been made into chocolate already then you can't really do much & I doubt it's residual solvent causing your problem, as sekio says the cooking process should remove any solvent if there was any left in the oil.
More likely the chocolate, or something else entirely (your meds, cancer...) made you sick.
If you have some of the raw oil you could heat it to remove any solvent, just don't heat it too much so you boil the THC & other goodies off it. It's very unlikely there is a significant amount of solvent left in your oil.
If the weed is left in alcohol for too long it'll extract more chlorophyll & other stuff from the plant material that wont get you high, but it wont affect how much solvent is left in the end product. A quicker wash will usually produce a purer cannabinoid oil.
Butane isn't inert, huffing butane isn't unknown (or healthy at all), but the amounts used to get any effect are much higher than could be left in any oil & 'rick simpson oil' should be made using ethanol, not butane.
If you do have some bad oil that was left to soak in alcohol for too long, it'll be pretty hard to fix, because leftover solvents aren't likely to be your problem - the solvent would just evaporate off. It's better to use oil or hash that was made better, I can't think of any easy ways to refine it. Higher quality oil can be made by not soaking the plant material for as long, using higher quality plant material, or using a different extraction method (butane, heat, ice/water, CO2, dry sift, etc).
If you just have that chocolate you could try mixing it with hot milk (or similar) to make it easier to digest.
Also, Rick Simpson doesn't sell oil, he just shares his method for making oil. If you bought some oil claiming to be 'Rick Simpson Oil' then it's likely you have been scammed & whatever you have might not even contain any cannabis. The only way to get 'Rick Simpson Oil' is to make it yourself from cannabis.