Health Organization for Pudendal Education

I saw my pain management consultant yesterday to review my progress with Pregabalin. I explained that as I increased the dose I got increased swelling in my calves and ankles during the day, plus I was having increasing thread veins in my legs. He said that both were known side effects but less common. He wants me to stop the Pregabalin and change to Gabapentin and to do this without stopping the Pregabalin. I have read posts about changing from Gabapentin to Pregabalin but not the other way round. Just wondered if anyone has tried the swop this way round and if so how did they get on.
Julia