You are taking unacceptable risk by consuming nimesulide. This drug was discovered in America but is not allowed to be sold there and most of the advanced countries such as Canada, Britain, Australia etc. In Finland, its use by some patients led to liver failure resulting in deaths and liver transplant.
There are so many medicines for pain and/or fever such as aspirin, diclofenac (sold under the trade name of Doflex), indomethacin (sold as Indocap), meloxicam (sold under the brand name of Mel-Od), etoricoxib (sold under the brand name of Nucoxia), celecoxib (sold under the brand name of Zycel) etc. etc.
For drug-related mild allergy, you can take the painkiller together with an anti-allergic agent such as cetirizine (Ceticad).