The 21 year-old penned a deal to extend his loan contract this afternoon after signing initially for a month.
He has previously confirmed he will be a free agent in the summer and won't be signing a new deal should one be offered by parent club Chelsea, as he searches for regular first team football.
Meanwhile the Millers are thought to be consulting with Reading over extening the loan of Brett Williams.
The striker will be in the squad for his final game at Dagenham this weekend.