More than one DbContext named 'NewProject.Models.DbContext' was found Specify which one to use by providing its fully qualified name using exact case

I'm leaving that question and answer here so people don't go crazy looking for all possible solutions manually like I did. I found out that adding the context in the Configure method of IdentityHostingStartup.cs was causing the problem. I changed the place where I added the context to the Configure method of Startup.cs and it was working just fine.

namespace ShareAndCare
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });            

            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

            services.AddDbContext<ShareAndCareContext>(options =>
                   options.UseLazyLoadingProxies().UseSqlServer(
                       Configuration.GetConnectionString("ShareAndCareContextConnection")));

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider serviceProvider)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseAuthentication();
            app.UseCookiePolicy();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });                
        }   
    }
}