You can fairly easily check what sort of penalty has been applied by checking the below;
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Does your site appear on google's first page for your domain name? If no then you may have had a penalty
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Does your site appear if you search for an exact phrase of about 5-6 words? If no then you probably have some sites linking in which have been devalued
You say that you've added a page of links; if these are spammy links then this could have a negative effect on your rankings. If google sees that you are in effect 'voting' for spammy sites it may devalue your sites status in itself (especially if your link profile isn't top notch).
I would work on creating some more, high quality links into your site and you should see the rankings restore to normal.
Google sometimes takes a few weeks to put your site back to where it belongs after something like this happens, and so you may need to wait a bit longer for it to bounce back.
If not you can always send a re-consideration request, even if your site isn't penalised; explain you made a mistake with the low quality links and you've now removed them. and they may restore value to your site