Cumulative volume across all exchanges might be tricky but Cryptsy has a API call in the V2 version which will get OHLCV series by day/hour/minute
Try this and use the volume info for the period of interest to you:
https://www.cryptsy.com/api/v2/markets/155/ohlc?interval=day
Yeah cumulative volume for all exchanges is what I was looking for, it indeed seems tricky. If anyone has any idea on how to get this info I would really appreciate it.
https://bitinfocharts.com/markets/
edit: sorry, you wanted "Volume data for DRK for the last 10 to 15 days". I don't think someone created a site with such a data. Would be useful