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Francisco, OSE won't always show all of your lowest quality links and what it does show may fluxuate.  In addition to OSE, take a look at links showing at majesticseo and ahrefs.com, and even your google webmaster tools to get a fuller picture of your back links and which you may want to disavow.

Hey Francisco, First and foremost, you should check why your traffic has dropped. Check whether it has dropped on a certain search engine or on a certain set of keywords or landing pages, or is it a blanket drop everywhere. Check whether your other sources of traffic have tanked as well (direct, referral, etc.) to see if you maybe have a website problem (Webmaster Tools can help you diagnose that as well). Also check some of the Moz reports available. Moz cannot read Google penalties, so your Domain Authority (as well as your traffic) might have dropped due to a sudden removal of a portion of your backlinks. As a side note, if your subdomain has been penalized due to spammy backlinks, there's a high likelihood your whole domain has been penalized as well.