My tattoo artist made a bit of a mistake...will this be hard to fix? (Picture)?

Sorry but your artist did a lousy job in general. This is exactly why you need to really research a tattoo artist before you go through with it. Yes you can fix it but you will need more than a good artist to fix it. You need a great one. So next time go to a major city in your area and ask around for the best tattoo artists and actually look at their art work.