Burning Sensation Normal After Botox and Restylane Injections?

From the sounds of it, this is most likely the early stage of a bruise. It is more likely to have been caused by the Botox rather than the Restylane injection.
Bruising in the forehead can occur with even the best injectors, if your skin is rather thick. Bruising from Botox can be adeptly avoided in the crow's feet, glabellar, and temple areas. However, the forehead skin is thicker and the vessels are often not as visible. Further, there are two schools of thought regarding Botox injections in the forehead. One says that you must go rather deep to insure that the muscle is injected properly. However, others attest that this increases the risk of the forehead complication you have experienced. Those physicians would advise one to inject more superficially, and message the Botox into the muscle.
If you are reading this on the day of the injection, I would use cool soaks to minimize further swelling. In the following days, lukewarm soaks should help. Some physicians would recommend arnica montana. I don't because I do not feel that this old folk remedy has enough science behind it.