Help!Please!My twitter account has been hijacked, I'm sure!?

[FaithPrevails]

Every now and then, maybe even every day, I get these random tweets "sent" by me that appear on my profile page. The irony is that I didn't even send these tweets. And the tweets are always the same message: Want to lose weight? click on this website... something like that-- I can't be sure as I always delete those tweets. I use hootsuite, so could hootsuite be posting these random tweets that are not sent by me? If the problem is hootsuite, then is there something similar to hootsuite?because I really need hootsuite. If hootsuite is the problem(I hope not) then can you suggest any other SAFE website that automates tweets for free? Is it any of my applications that I use? I'll list all of them here:
read and write access · Approved: Sun October 23, 2011 15:31:52

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Goodreads by Goodreads
Goodreads is a place where you see what your friends are reading. Organize what you've read, list your favorite books, discuss literature, form groups, and connect with other readers.
read and write access · Approved: Tue October 18, 2011 14:10:08

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TwitLonger Beta by TwitLonger
Beta site for testing new features for TwitLonger
read and write access · Approved: Mon October 17, 2011 12:04:57

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Yahoo! by Yahoo!
Yahoo! Frontpage Twitter application
read and write access · Approved: Sat October 1, 2011 18:52:25

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Twitpic by Twitpic Inc
Share photos on Twitter with Twitpic
read and write access · Approved: Sat October 1, 2011 09:56:35

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HootSuite by HootSuite
The social media dashboard which allows teams to broadcast, monitor and track results.
read, write, and direct messages access · Approved: Sat September 24, 2011 09:05:42

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twitroundsdotcom by http://twitrbackgrounds.com
Change your backgrounds.
read and write access · Approved: Mon September 19, 2011 12:51:09

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BackupMyTweets by BackupMy, Inc.
BackupMy.Net is a suite of web backup products to backup your online info. BackupMyTweets is the BackupMy.Net Twitter backup service.
read and write access · Approved: Fri September 16, 2011 17:59:48

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WeFollow by WeFollow
A user powered Twitter directory.
read and write access · Approved: Fri September 16, 2011 17:35:03

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Kindle by Amazon Services LLC
This application allows Kindle customers to post their favorite passages along with their thoughts on those passages to Twitter directly from their Kindle.
read and write access · Approved: Sat August 13, 2011 20:50:30

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Twitter for BlackBerry® by Research In Motion Limited
Twitter for BlackBerry® smartphones helps you stay in touch anywhere, anytime. You can post a tweet, follow other Twitter users, search, upload photos and more
read, write, and direct messages access · Approved: Fri July 15, 2011 10:11:07


Thanks in advance for answering.

[UncleP]

You DO know you can change your password right? You'd find these mysterious tweets would stop then, as if by magic!