I have had costchondritis for about six months. The pain goes from intense to moderate. The big problem, however, is that whenever I doing any sort of activity I get shortness of breath and a rapid heartbeat. I can t walk 20 feet without these symptoms occurring. I ve tried deep breathing, shallow breathing but that hasn t helped. I ve been taking 600 mg gabapentin for about 2 months now. I m constantly tired, light-headed and occasionally dizzy. I wasn t sure if this is because of the lack of oxygen due to shallow breathing or if it could be the gabapentin