Sumatriptan injection side effects

Hi not sure if I'm posting in the right place sorry in advance I have suffered for nearly 3 years with CH I'm (25). Very recently I have been given sumatriptan injections that work really well and relieve a bout in about 10-15mins previously I have been using oxygen for the pain relief but takes a lot longer the relieve the pain. I'm getting some horrible side effects from the sumatriptan injections and I'm just wondering if they are normal. Firstly I will go a little light headed followed by a hot flush then like my chest has gone tight as well as being a bit drowsy for about half an hour in have used the injections several times now and still having the same side effects thanks if anyone can help me out