I am having the same issue with mine (Latitude e7450) with low playback after using a mic for recording. I am not using it for the purpose of skyping but rather for recording narration on powerpoint and articulate files. I have reinstalled articulate and ppt and there is no change. I have ensured that the recording levels are maxed in the Dell audio settings. Any help would be appreciated, since this is for work!
If you do have Skype on your computer (even though you don't use it) it might be useful to make use of the Microphone testing service that it provides to test your microphone and see if it suggests a fix for the low volume. Just a thought. is this situation after installing Windows 10?. If so, it could well be related.