The 20-year-old arrived in Scotland on Tuesday morning and could feature against Aberdeen in the Clydesdale Bank Premier League on Wednesday.
Wales Under-19 international Doughty, who has made one first-team appearance for QPR and has had loan spells at Aldershot and Crawley, comes in after winger Peter Pawlett was recalled by the Dons following his loan spell at McDiarmid Park.
Murray Davidson is a doubt for the visit of Aberdeen with an ankle injury while defenders Gary Miller (ankle) and Steven Anderson (knee) remain out.
Lomas recently released striker Craig Beattie and would like to add to his squad before Thursday's transfer deadline but knows that is unlikely in the club's financial situation.
Lomas told Press Association Sport: "We have taken young Michael Doughty from QPR. They have kindly let us have Michael. Michael's a very silky midfielder who is good on the ball and can play in various positions across the middle.
"We are very thin on the ground. We have lost Gary Miller for eight weeks. Steven Anderson is still getting back from his cartilage operation and will be at least another couple of weeks."
When asked if he would be looking to bring in another player, Lomas said: "It is down to the chairman and (associate director) Roddy Grant.
"I have let them know what my feelings are. We are taking a huge gamble in the second half of the season with the number of players we have got, but that's not down to me.
"I can only make my recommendations and it's down to them. I understand there are more cuts needed in the budget. That's the way it is and we have got to get on with it. But I do think we are taking a very, very big gamble. We have probably got the smallest squad in the SPL."
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- Clydesdale Bank Premier League
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