The secure connection message just notes all your pages are not resolving over an SSL certificate. You have access to a free SSL through Reclaim thanks to Let’s Encrypt, you can install that if you haven’t already. Installing Free SSL Certificates
After that, if some images or pages re still not loading securely, try the Really Simple SSL plugin:
Now, as far as Akismet, that is trickier. Akismet finding false positives wouldn’t have as much to do with the SSL warning as it would with just training the machine. While Akismet is good, it is far from perfect, and you do need to check your spam before mass deleting. This often mean, more likely than not, some comments inevitably get lost. Other than that, I would just confirm your API key through Akismet, and keep an eye on things.